To treat cardiac insufficiency or failure, heart assist devices have been used to assist the heart of a patient. These heart assist devices include various pumping devices. A high level of success has been attributed to a particular group of heart assist devices called rotary blood pumps.
In the past, the rotary blood pumps have used control systems which set the pumping speed at a constant rate. This constant rate would not change for the physiological demands of the patient. Therefore, if a patient was exercising the physiological demands for increased blood supply would not be offset by a matched increased pumping rate or speed of the rotary blood pump.
Therefore, there is a need for a control system that allows a rotary blood pump to match the physiological needs of a patient.
Rotary blood pumps also usually provide a continuous flow which is additionally pulsed by the residual function of the patient's heart. Rotary blood pumps operating at predetermined fixed pumping rate often tend to over-pump or under-pump blood from the ventricle depending on the physiological needs of the patient and this may lead to deleterious effects on the patient including, but not limited to, suction events or ventricular collapse. Suction events occur where the pressure within a ventricle is less than the intrathoracic pressure around the heart. The net result is a partial or complete collapse of the ventricle.
The present invention aims to or at least address or ameliorate one or more of the disadvantages associated with the above mentioned prior art, or to provide a useful alternative.